Improved SMS islanding detection method for grid-connected converters

In this project, the popular slip mode frequency shift (SMS) and auto phase shift active islanding detection methods are investigated and an improved (IM)-SMS strategy is proposed in this study. In the proposed method, additional phase shift is introduced to help in stimulating the action of the islanding detection and the algorithm is simplified as well. When the utility grid is disconnected, the algorithm keeps the frequency of the converter output voltage deviating until the frequency protection relay is triggered. The working principle of the method is introduced and the guidance of parameters selection and optimization is also provided. The islanding detection performance is evaluated through theoretical analysis and verified by digital simulation and experimental results. The IM-SMS method exhibits features of simplicity, easy implementation and high reliability. The simulation results of this method can be evaluated by using Matlab/Simulink Software.

Keywords: —Grid connected converter, current controller, IM-SMS, islanding mode.